Dietmar Nill / Barn Swallow (Hirundo rustica) and House martin (Delichon urbica) collecting nesting material, Bulgaria

Kerstin Hinze / House Martin (Delichon urbica) flying with mud in bill to use as nesting material, Bulgaria

Kim Taylor / Bird flea (Siphonaptera sp) on the feather of a House Martin (Delichon urbica) Surrey, England

Mike Read / House martin at nestbox {Delichon urbica} UK